The United Nations says tens of thousands of civilians are still trapped in the Old City of the Iraqi city of Mosul, where U.S.-backed troops have recaptured more neighborhoods.

Hundreds of civilians are fleeing the onslaught, which began June 6. Major General Sami al-Aridi said Iraqi forces are just a few hundred meters from the banks of the Tigris River, as U.S.-led coalition aircraft pounded Islamic State fighters on July 2.

Soaring temperatures are compounding the misery of trapped civilians, who are facing food and water shortages.

Iraqi joint forces spokesman Yahia Rasoul on July 1 told state-run TV that Islamic State fighters now control just "a few residential areas.”

The Islamist extremists seized Mosul from Iraqi government forces in June 2014 as they captured large segments of territory across Iraq and neighboring Syria, declaring an Islamic “caliphate” over areas they controlled.

But U.S.-backed forces have made steady progress against IS in both countries over recent months. In addition to the assault on Mosul, U.S.-backed forces are closing on fighters in Raqqa, their stronghold in Syria.

On June 29, Iraqi Prime Minister Haidar al-Abadi declared an end to IS'a self-declared caliphate as his forces squeezed the militants into a few streets in Mosul’s Old City.